Synthesis and Characterization of Nickel(II) and Palladium(II) Complexes based on Tridentate [N-NP] and [N-NS] Ligands and Their Applications in Norbornene Polymerization

The series of anilido-imine N-NP and N-NS tridentate nickel and palladium complexes [(ArNHC6H4CH=NPh-2-XPh)MCl] (X = PPh, Ar = 2,6-Me2C6H3, M = Ni (2a), X = PPh, Ar = 2,6-Et2C6H3, M = Ni (2b); X = PPh, Ar = 2,6-i-Pr2C6H3, M = Ni (2c); X = S, Ar = Ph, M = Ni (2d); X = S, Ar = 2,6-Me2C6H3, M = Ni (2e); X = S, Ar = 2,6-i-Pr2C6H3, M = Ni (2f); X = PPh, Ar = 2,6-Me2C6H3, M = Pd (3a); X = PPh, Ar = 2,6-Et2C6H3, M = Pd (3b); X = PPh, Ar = 2,6-i-Pr2C6H3, M = Pd (3c)) were synthesized. All the complexes were fully characterized by IR, NMR and elemental analyses. X-ray diffraction analyses on complexes 2a,c and 3a revealed an almost square-planar coordination of the central metal. After activation with methylaluminoxane (MAO), the nickel(II) complexes 2a-f can be used as catalysts for norbornene polymerization to produce vinyl addition type polynorbornene (PNB) with high catalytic activities, up to 5.82 X 10(7) g of PNB (mol of Ni)(-1) h(-1), while poor catalytic activities are found for the palladium complexes 3a-c.